* {
    margin: 0;
    padding: 0;
}

#container {
    width: 620px;
    height: 420px;

    margin: 50px auto;
    position: relative;
    background-color: yellowgreen;

    overflow: hidden;
}

#container a:hover{
    opacity: 1.0;
}

#imgList {
    /*设置width时，我们希望实现动态设置，因此用js改变width的值*/

    display: inline-block;
    /*删除项目符号*/
    list-style: none;
    left: 0px;
    position: absolute;
}

#imgList li {
    float: left;
    margin: 10px 10px;
}

#button {
    position: absolute;
    bottom: 20px;
    left: 0px;
}

#button a {
    width: 20px;
    height: 20px;
    background-color: red;
    float: left;
    /*设置左右外边距*/
    margin: 0 10px;
    opacity: 0.5;
}

.arrow {
    width: 36px;
    height: 50px;
    background-color: black;
    opacity: 0.2;
    position: absolute;
    z-index: 1;
    font-size: 50px;
    font-weight: bold;
    color: aliceblue;
    cursor: pointer;
}

#button a:hover{
    background-color: black;
}

